Experimental study of CO2 and N2 adsorption on activated carbon

Abstract

The present study as designed to assess the CO2 and N2 adsorption isotherms on activated carbon (AC). The AC was characterized with SEM, XRD and N2 isotherm. The CO2 and the N2 adsorption experiments on the AC are performed at 298, 308 and 328 K and modelled by Langmuir model. The preferred selectivity (α CO2/N2) was obtained with the use of the Langmuir properties and the Henry coefficient (K H ) was found from the virial equation. The thermodynamic analysis of CO2 and N2 adsorption which include the entropy loss (ΔS), the Gibbs free energy change (ΔG) and the surface potential (Ω) was calculated. The results reveal that the order of CO2 uptake on AC is higher than that of N2. α(CO2/N2) decreased with the increase of the temperature. The KH values of CO2 on the AC are the most important, while the KH values for N2 are the least. The thermodynamic parameters which include Ω, ΔG and ΔS are impacted by the porous structure of the AC.The adsorption affinity and the adsorption spontaneity of CO2 is the highest, while N2 has the lowest adsorption spontaneity. Subsequently, CO2 exhibits a higher interaction with AC, in contrast to N2 which displays a slight interaction.the obtained results can be used to CO2 capture and to improve the efficiency of CO2 adsorption devices.